Weakened flu defence killed 50 children in last five years
Around 50 children have died from flu in the past five years, including some who were healthy and had no previous risk factors.
The Health Service Executive (HSE) confirmed that up to 10 victims under the age of 16 die each year from winter flu.
The highest risk of complications is to children who have pre-existing conditions that make them vulnerable, such as asthma and heart disease.
Nine years ago, during the Europe-wide swine flu pandemic, there was a particularly high death rate among the young as children who had no previous health difficulties were killed by the virus.
"We are not all built the same way," said Trinity College immunologist Seamus Martin.
"There is natural variation in our resistance. Certain flu strains may be able to breach the immune defences of otherwise healthy people."
Prof Sam McConkey, a consultant in infectious diseases at Beaumont Hospital, said that if a patient gets pneumonia on top of flu, it can be a major worry.
"A patient can get the flu first and then bacterial double pneumonia," he said.
"That can lead to failure of the lungs and death. Sometimes they can go blue and fluid builds up in the lungs.
"You need to be in hospital and intensive care at that stage."
He added that this year some of the sickest patients with flu have low oxygen in their blood.
They are given anti-viral medication and after a day or two are well enough to go home.
The impact on patients this winter has not been as severe as during the swine flu pandemic of 2009.
The flu outbreak this year in Ireland has been "moderate to severe".
So far, hospitalisations have been highest among the over-65s and babies less than a year old.
Premature babies can also be at high risk from the flu.
Prof Joe Keane, a respiratory consultant at St James's Hospital, said the flu causes a patient's immune system to be suppressed.
"It interferes with the person's normal ability to fight bacteria," he said.
"They suspend your immunity against bacteria.
"So an ordinary bacteria with which you would normally deal quite easily becomes a life-threatening infection.
"You start off with what appears to be a transient viral infection, but what that does is destroy the lining of the lung which ordinarily prevents the bacteria from taking root in your lungs.
"The consequence of that is a person who is immuno suppressed with bacterial pneumonia and that is a bad combination."
However, Prof Keane said that dying from flu was a very rare event.
"That is why we are keen on vaccination," he added.
Meanwhile, there was little respite for the country's A&E departments yesterday as 506 patients waited on trolleys for a bed.
A lack of beds has forced 73 children to languish in emergency departments in the past two weeks.
The young patients have endured hours on trolleys in Our Lady's Children's Hospital, Crumlin, the National Children's Hospital, Tallaght, and the Children's University Hospital, Temple Street.
The figures were released by the Irish Nurses and Midwives Organisation (INMO), which launched its new trolley watch for children's hospitals.